It's understandable blue control players would be shocked and in denial at the notion of this card, since their decks have been dominating multiple formats for an eternity yet they've curiously never once had to deal with any counter-hosers that weren't ineffectual, narrow CRAP.
I would think so, yes. You tap it for 0, then can play it for free. It's an alternate cost. Like if there was a card that says you can play a card without paying its mana cost, than you would be able to play it for free. Yay free 3 cards every turn!
"If an alternative cost is applied to an unpayable cost, including an effect that allows you to play a spell without paying its mana cost, the alternative cost may be paid."
MTG Rules adviser.
"If an alternative cost is applied to an unpayable cost, including an effect that allows you to play a spell without paying its mana cost, the alternative cost may be paid."
Altered Cards! Crafts and Stuff!